Management apparatus, energy storage apparatus, and energy storage system

Abstract

A management device 21 comprising a main control part 23 that, during charging of a plurality of power storage elements 41 connected in series, outputs a first pull-down signal to a converter 11 so as to lower a charging voltage when the cell voltage of any of the power storage elements 41 is equal to or greater than a first threshold value.

The invention claimed is: 
     
       1. A management apparatus comprising a control unit in communication with a charger that performs constant current constant voltage charge, the control unit being configured to:
 perform constant current charge control after the start of charge and before a total voltage of a plurality of energy storage devices connected in series reaches a predetermined voltage value; 
 when the total voltage reaches the predetermined voltage value:
 (i) switch to constant voltage charge control in which the total voltage is maintained; and 
 (ii) gradually decrease a charge current of the plurality of energy storage devices; and 
 
 when, during the constant voltage charge control, a voltage of any of the plurality of energy storage devices becomes equal to or higher than a first threshold, give to the charger a lowering notification to lower charge voltage, 
 wherein the charger controls charge on a basis of the maintained total voltage of the plurality of the energy storage devices. 
 
     
     
       2. The management apparatus according to  claim 1 , wherein
 each of the plurality of the energy storage devices has:
 a low-change area in which a rate of change of an open circuit voltage with respect to a state of charge is relatively low; and 
 a high-change area in a high charge state, the high-change area being in a state of charge higher than the state of charge of the low-change area and having a relatively high rate of change of the open circuit voltage with respect to the state of charge than the rate of change in the low-change area, and 
 
 the first threshold is included in the high-change area in the high charge state. 
 
     
     
       3. The management apparatus according to  claim 1 , further comprising a discharge circuit that allows the plurality of the energy storage devices to discharge electricity individually, wherein the control unit allows, among the plurality of the energy storage devices, only an energy storage device in which a voltage becomes equal to or higher than a third threshold to discharge electricity by the discharge circuit. 
     
     
       4. The management apparatus according to  claim 1 , wherein, after the charge voltage is lowered, when the voltage of any of the plurality of the energy storage devices is equal to or higher than the first threshold, the control unit gives a stepwise lowering notification to the charger to further lower the charge voltage. 
     
     
       5. The management apparatus according to  claim 4 , wherein the control unit gives the stepwise lowering notification a plurality of times to lower the charge voltage in multiple steps. 
     
     
       6. The management apparatus according to  claim 1 , wherein, when the voltages of all of the plurality of the energy storage devices are equal to or lower than a second threshold, the control unit gives, to the charger, a restoration notification to restore the charge voltage to an initial value. 
     
     
       7. The management apparatus according to  claim 6 , wherein the control unit performs a process of informing abnormality when the charger repeats adjustment of the charge voltage either a predetermined number of times or a predetermined period of time or longer. 
     
     
       8. The management apparatus according to  claim 1 , wherein, when a voltage difference between the plurality of the energy storage devices is equal to or less than a predetermined value, the control unit gives a restoration notification to restore the charge voltage of the charger to an initial value. 
     
     
       9. The management apparatus according to  claim 8 , wherein the control unit performs a process of informing abnormality when a state in which the charge voltage is lowered continues for a predetermined period of time or longer. 
     
     
       10. An energy storage apparatus comprising:
 one or a plurality of energy storage blocks connected in series; and 
 the management apparatus according to  claim 1 , 
 wherein each of the energy storage blocks includes a plurality of energy storage devices connected in series. 
 
     
     
       11. An energy storage system comprising:
 a charger; 
 the energy storage apparatus according to  claim 10 ; and 
 a charge path that connects the charger and the energy storage apparatus. 
 
     
     
       12. The energy storage system according to  claim 11 , wherein:
 in response to the lowering notification, the charger lowers the charge voltage from an initial value, and 
 the charge voltage after the lowering is included in the high-change area in the high charged state in terms of a voltage per one of the plurality of the energy storage devices. 
 
     
     
       13. The energy storage system according to  claim 11 , wherein a charge control circuit that controls charge of the energy storage apparatus is not provided on the charge path. 
     
     
       14. The energy storage system according to  claim 11 , further comprising:
 the energy storage apparatus connected to a power supply line for supplying electric power from a main power source to a load via a branch line; and 
 a power converter provided on the branch line, 
 wherein:
 the power converter is a bidirectional power converter that:
 converts part of electric power supplied from the main power source and outputs a charge current to the energy storage device, and 
 converts electric power supplied from the energy storage device to output a discharge current to the load, and 
 
 when the voltage of any of the plurality of the energy storage devices of the energy storage apparatus becomes equal to or higher than the first threshold, the control unit gives the lowering notification to the power converter to lower the charge voltage.